Process for the manufacture of ammonia by means of aluminium nitrid.



'UNITED STATES PATEN OFFICE.

OTTOKAR SERPEK, OF PARIS, FRANCE, ASSIGNOR TO SOCIETE GENERALE DESNITRURES, OF PARIS, FRANCE.

PROCESS FOR THE MANUFACTURE OF AMMONIA BY. MEANS OF ALUMINIUM NITRID.

No Drawing.

Patented Oct. 8, 1912.

To all whom it mayjconcem Be it known that I, OTTOKAR SERPEK, of. 12 RueRoquepine, Paris, France, chemical engineer, have invented a certain newand useful Process for the Manufacture of Ammonia by Means oi AluminiumNitrid, of which the following is a full, clear, and exact dwcription.

Nitrid of aluminium is a body fairly resistant to water. At ordinarytemperatures -it decomposes in water givin oil ammonia in a; mannerhardly perceptible and it is only in boiling water that the evolution ofammonia begins to become appreciable; but even under pressure andconsequently at temperatures higher than 100 0., it requires a fairlylong time to obtain a considerable yield of ammonia.

It has already been proposed to obtain ammonia by mea'ns of aluminiumnitrid by decomposing the latter by solutions of alkaline aluminate.This being so, the present invention is based upon the followingobservation, viz. that it is possible to work with solutions ofaluminate in which the content of alkali is less than that which isnecessary to render .soluble the alumina resulting from thedecomposition of the aluminium nitrid treated. Consequently it is alsopossible to employ over again as they are, the weak alkaline lyesresulting from the preceding operations, so as to be able to suppress inthis way the losses of alkalis and the expense necessitated by theconcentration of the Weak lyes.

This process can be applied to all nitrids which can be decomposed byalkalis and of which the decomposition yields saline solutions in adissociated state, for instance to the decomposition of nitrogenouscompounds by solutions of alkaline silicates.

- Example: 100 kilograms of aluminium nitrid with a content of 28 percent. of nitro-.

gen (that is to say a nitrogenous product containing 82 per cent. ofaluminium nitrid) are introduced into 200 kilograms of a solution ofaluminate which contains 20 per cent. of potassium hydrate. The whole isbrought .more rapidly.

to boiling point with continual stirring.

Ammonia 1s given off in a strong and regu lar manner. l ter boilingthere remains precipitated alumina which contains practically nonitrogen. It is preferable to eflect the boiling under pressure.Theoretically the quantity of nitrid above would have necessitated about100 kilograms of alkali. In practice, 40 kilograms of. potassium hydratehas been sufficient, which moreover has not been employed in the freestate but in the form of a salt (aluminate). After the completedecomposition and the'separation of the solution of precipitated aluminaand if necessary after dilution of the latter with water up to 200kilograms, this solution can serve again to decompose IOO'kilograms ofnit-rid, etc. In the same way the alumina separated from the solutioncan be treated so as to re-form nitrid.

Speaking generally, if I add small quantities, as for example, evenmerely traces, of-alkalis, to an aqueous solution -in the presence ofaluminium nitrid, the decomposition of the latter is made in a completemanner, as if with water alone but much The alkali, whether free or inthe form of aluminate, attacks the nitrid V with disengagement of NH andprecipitation of A1 0 coming from the nitrid decomposed. In short,traces of alkali suflice to provoke complete and rapid decomposition oflarge quantities of aluminium nitrid. I claim as my invention As animprovement in the process of pro-' ducing ammonia, subjecting aluminiumnitrid to the action of a solution of aluminate of which the content inalkali is less than that which is necessary to render soluble thealumina resulting from the decomposition of the aluminium nitridtreated.

In testimony whereof I have signed-my name to this specification, in thepresence of two subscribing witnesses.

OTTOKAR SERPEK.

Witnesses:

H. C. Coxn, LEON PEILLET.

